Referring to FIG. 1, a conventional slide rail structure for mounting industry-used computers comprises a plurality of slide plates, each having a width between 1.6 to 2 cm and therefore taking an appreciable space. This will hinder the installation of a computer when the inner space of a cabinet is tight. Further, the conventional rail structure is complicated and difficult to assemble, resulting in a high production cost. The multiple slide pieces also require higher manufacturing precision, causing a higher fault rate when they are in service. Referring to FIG. 2, a simple rail structure disclosed by the R.O.C. patent number 89216454 aiming at improving the above problems has a base (A) and a slide element (B, which consists of a single piece), integrated by punch casting. The structure is simple but still complicated to make. For example, the punch casting will result in unsmoothness about a folded section, making the fold angle control difficult. The imperfection caused by the punch casting would cause unsmooth slide motion of the slide elements relative to the base and a large friction therebetween.